The invention relates to an inductively coupled method and apparatus of communicating with wellbore equipment.
A major goal in the operation of a well is improved productivity of the well. The production of well fluids may be affected by various downhole conditions, such as the presence of water, pressure and temperature conditions, fluid flow rates, formation and fluid properties, and other conditions. Various monitoring devices may be placed downhole to measure or sense for these conditions. In addition, control devices, such as flow control devices, may be used to regulate or control the well. For example, flow control devices can regulate fluid flow into or out of a reservoir. The monitoring and control devices may be part of an intelligent completion system (ICS) or a permanent monitoring system (PMS), in which communications can occur between downhole devices and a well surface controller. The downhole devices that are part of such systems are placed in the well during the completion phase with the expectation that they will remain functional for a relatively long period of time (e.g., many years).
To retrieve information gathered by downhole monitoring devices and/or to control activation of downhole control devices, electrical power and signals may be communicated down electrical cables from the surface. However, in some locations of the well, it may be difficult to reliably connect electrical conductors to devices due to the presence of water and other well fluids. One such location is in a lateral branch of a multilateral well. Typically, completion equipment in a lateral branch is installed separately from the equipment in the main bore. Thus, any electrical connection that needs to be made to the equipment in the lateral branch would be a “wet” connection due to the presence of water and other liquids.
In addition, because of the presence of certain completion components, making an electrical connection may be difficult and impractical. Furthermore, the hydraulic integrity of portions of the well may be endangered by such connections. One example involves sensors, such as resistivity electrodes, that are placed outside the casing to measure the resistivity profile of the surrounding formation. Electrical cables are typically run within the casing, and making an electrical connection through the casing is undesirable. Resistivity electrodes may be used to monitor for the presence of water behind a hydrocarbon-bearing reservoir. As the hydrocarbons are produced, the water may start advancing toward the wellbore. At some point, water may be produced into the wellbore. Resistivity electrodes provide measurements that allow a well operator to determine when water is about to be produced so that corrective action may be taken.
However, without the availability of cost effective and reliable mechanisms to communicate electrical power and signaling with downhole monitoring and control devices, the use of such devices to improve the productivity of a well may be ineffective. Thus, a need exists for an improved method and apparatus for communicating electrical power and/or signaling with downhole modules.